Mayonnaise is a water continuous emulsion, containing 80 wt. % of dispersed oil. In order to impart proper stability and texture to mayonnaises with a reduced fat content, particularly 40 wt. % or less, it is necessary to incorporate auxiliary ingredients in the mayonnaise, particularly lipid emulsifiers and polysaccharide thickeners, such as gums and starch derivatives. Often, however, the thickeners have an adverse effect on taste and mouthfeel. Moreover, such auxiliary ingredients have to be declared on the label, unless they are considered natural. Presently, many consumers prefer industrially prepared food to have a minimum amount of added emulsifiers and thickeners. It is a problem to find natural ingredients with a functionality which can impart to low fat food dressings in general, and to low fat mayonnaise in particular, a smooth, either spoonable or pourable, rheology.
The solution mentioned in JP 06/054 662 (KAO Corp.) realizes a proper texture by using 1 to 10% of egg, milk or soyabean derived protein, which is dissolved in a water continuous emulsion containing 10 to 60 wt. % of dispersed oil. For maximum thickening, the pH of the dressing is adjusted to the protein's isoelectric point which is, however, much higher than the optimum pH for microbiological stability. When lowering to the optimum pH for microbiological safety, the thickening effect quickly disappears and a dressing results which is too thin. Moreover, the oil droplets of this prior art's dressing should be comminuted so that greater than 80% of them have an extremely small size of less than 1 .mu.m, otherwise no proper texture is obtained.
The article `Whey protein and the properties of salad dressing` in Deutsche Milchwirtschaft, 1993, 44(21) p. 1054, by G. Muschiolik et al, discusses the effects of pH and salt content on protein-stabilised emulsion systems. It states that the addition of salt has little or no influence on the consistency of systems containing acid, such as salad dressings. From FIG. 3, it is apparent that the addition of salt either before or after high-pressure homogenisation has little effect on the consistency of systems containing acid.
Similar conclusions are reached in the article `Investigation of the function of whey protein preparations in oil-in-water emulsions` by G. Muschiolik et al, from Proc. Food Macromolecules and Colloids Symposium, 1994, Dijon, which also discusses the effects of pH and salt content on protein-stabilised oil-in-water emulsions.
The article `Heat stability of oil-in-water emulsions containing milk proteins: effect of ionic strength and pH` by Hunt and Dalgleish, in the Journal of Food Science, Vol. 60, No. 5, 1995, p. 1120 examines the heat-stability of acidic emulsions containing whey protein and KCl.
The present invention seeks to provide a process for preparing an improved aqueous-continuous emulsion.